In order to set implants in a jaw permanently and firmly, the jawbone, at the appropriate point, has to be sufficiently wide and also strong enough. In other words, bone has to be present in sufficient quantity as well as quality.
If there is insufficient bone available for a secure anchoring of a sufficiently large or long implant, a so-called jawbone build-up must be provided. In such cases, increasing bone height is regarded as particularly problematic. Different methods are used for harvesting bone.
In case of a slight lack of bone width, the bone required for the jawbone build-up can be harvested during the operation. Bone replacement material can also be used or the additive amount can be extended by mixing bones and replacement material. This augmentation region is frequently protected with a flexible membrane, and so the bone can heal unimpeded. Further methods are bone spreading, bone splitting, bone block transplantation, sinus lift, cavity techniques, to some extent also with the use of bone replacement materials and protective membranes, and socket preservation.
From a biological point of view, an autologous spongiosa graft is the best replacement material for a bone. However, the availability of such grafts is limited and they show a high resorption rate after transplantation.
The materials and techniques used in the prior art frequently provide insufficient bone quality, and so implants are not securely anchored in their implant sockets. In addition, the bone replacement is frequently not sufficiently vascularized, which increases the risk of infection and affects the regeneration of the bone. In addition, growth factors are frequently used in methods from the prior art, which significantly increase the costs for the procedures.
Instead of using a bone replacement, missing bone substance can to some extent also be filled through bone regeneration. Segmental interruptions of the bony continuity on long bones can thus be treated by means of distraction osteogenesis.
Callus distraction has already been known for more than a hundred years. The most important biological stimulus for bone formation is mechanical load. It releases piezoelectric forces which activate osteoblasts and osteoclasts. Distraction osteogenesis induces the bone regeneration by triggering growths stimuli through slow separation of bone segments. With this method, distraction leads to the direct formation of woven bones. The defined tensile stress during bone generation is essential. If such a defined tensile stress is applied to bone fragments, the mesenchymal tissue in the gap and the adjoining fragment ends shows osteogenic potential. If sufficient vascular potency is present, progressive distraction results in metaplasia of the organized hematoma, also called blood coagulum, in a zone of longitudinally arranged, fibrous tissue which, under optimal external and internal conditions, can directly transform into woven bones. However, this is aggravated by the fact that the bone tissue is subject to a highly complex control during its regeneration.
WO 03/051220 A2 describes a method for distracting a jawbone by means of bone segments.
DE 10 2010 055 431 A1, WO 01/91663 A1, and U.S. Pat. No. 5,980,252 describe devices and methods for callus distraction by means of artificial interfaces, for example membranes. The membranes used in these methods are plane plates or platelets which in most cases are made of a metal, for example titanium. The membranes are moved by different devices and actuating elements, such as screws or wire rope hoists. These actuating elements are to some extent very complex or the lifting of the membrane can only be adjusted insufficiently. Furthermore, in order to move the membrane, the actuating element must frequently be anchored on adjacent teeth or in the bone. This leads to additional treatment or even surgical steps.
U.S. Pat. No. 6,537,070 B1 discloses a multipiece implant which is supposed to generate distraction osteogenesis by unscrewing the individual parts. However, this is at best limited to the direct region of the implant thread. A typical bone defect which affects the entire width of a tooth gap is thus not refillable. Additionally, for a distraction, a part of the implant body must be rotated in the bone tissue and/or in the region of the adjacent mucosa which is unfavorable for the healing process and bone formation.